Updated to Lollipop today on a verizon S5 but now gmail is not retrieving emails. If I open gmail and manually refresh they appear. Tried clearing cache and rebooted several times but still not working right.
How often do you have it set to sync? If you set it to sync, say, every hour, and check it every 15 minutes, it'll sync when you open the app, so it'll look as if it's not syncing.